<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- <button onclick="this.innerHTML=Date()">现在的时间是？</button>
    <button onclick="displayDate()">现在的时间是？</button> -->
    <p id="p1"></p>
    <script>
       //假值有： 0 false null undefined ""(空的字符串)
       //真值有： []空数组 {}空对象 function  / /空正则 ture
       console.log(100 || "111" || "" || 1); 
       console.log(1000 && " " && 0 && 11);
       console.log(22 && " "&& [] && / / && false);
        var a = null;
        var b = undefined;
        // console.log(a==b);//true
        var c = "";     //假值空字符串
        var d = 1;       //number
        var e = "a123"; //字符串
        var f = 0;
        console.log(d>e);//false
        // console.log(true+false);

        console.log((a==b) + !!(d>e) - c);
        console.log(b==c);
        console.log(a==f);
        console.log(30 & 37);
        console.log(45 | 22);
        var num = prompt("亲输入");
        if (num>=90) {
            console.log("优秀")
        }else if(num>=70){
            console.log("良好");
        }else if(num<=60){
            console.log("不及格");
        }
        var ww = 0/0;
        console.log(ww);
        var ff= 3;
        ff%=4;
        console.log(ff);
        
        console.log(1&2) ;
    //     document.getElementById("p1").innerHTML=text;

    //     for (i = 0; i < cars.length; i++) { 
    //     text += cars[i] + "<br>";
    //  }
     </script>
</body>
</html>